Megastorms on Saturn rage for centuries and leave marks

Hundred-year storms on Earth? On Saturn, that’s how long megastorms last, according to a new report from the National Science Foundation.

Jupiter’s iconic Great Red Spot is a megastorm that spans 10,000 miles in width and has been raging for at least 342 years, according to NASA. It is the largest known storm in our solar system. 

In a new study, experts have revealed that Saturn – despite its unassuming appearance – also experiences lingering megastorms that leave marks on its atmosphere for centuries.

Studying Saturn’s megastorms

The research, conducted by astronomers from UC Berkeley and the University of Michigan, was focused on radio emissions from Saturn, which come from below the surface. The results unveiled long-term disruptions in the distribution of ammonia gas.

The phenomenon of megastorms on Saturn, which arise roughly every two to three decades, bears a resemblance to Earth’s hurricanes in terms of their cyclonic nature, but on a massively amplified scale. 

Understanding gas giants

Curiously, the driving force behind Saturn’s megastorms is a mystery. What is understood, however, is that Saturn’s atmosphere is dominantly composed of hydrogen and helium, with smaller quantities of methane, water, and ammonia.

Imke de Pater of UC Berkeley has invested over four decades in studying gas giants. The focus of his research is to better understand the composition of these planets and what makes them unique, using the Karl G. Jansky Very Large Array to probe the radio emissions from deep inside the planet.

A new perspective 

Study lead author Cheng Li noted that the latest findings from Saturn offer a profound perspective.

“Understanding the mechanisms of the largest storms in the solar system puts the theory of hurricanes into a broader cosmic context, challenging our current knowledge and pushing the boundaries of terrestrial meteorology,” said Li. 

“At radio wavelengths, we probe below the visible cloud layers on giant planets. Radio observations help characterize dynamical, physical and chemical processes.”

The researchers found something very unexpected in the radio emissions from Saturn – anomalies in the concentration of ammonia gas in the planet’s atmosphere. The experts connected these abnormalities to past occurrences of megastorms in the planet’s northern hemisphere.

Conclusions about Saturn’s megastorms 

The team’s observations reveal that while ammonia concentrations dip at mid-altitudes, they show an enriching trend at lower altitudes, ranging from 100 to 200 kilometers further down. 

This shift in ammonia distribution is believed to be the result of precipitation followed by evaporation processes – effects that can persist for centuries.

The Karl G. Jansky Very Large Array, part of the National Radio Astronomy Observatory, is a prized facility under the U.S. National Science Foundation.

Mysteries of Saturn

Many other mysteries of the fascinating planet Saturn still await exploration and understanding by scientists.

Hexagon storm on the north pole

Saturn’s north pole hosts a hexagon-shaped storm that has been persistent for decades, if not longer. 

Each side of the hexagon is approximately 13,800 kilometers (8,600 miles) long. Scientists are uncertain how such a geometrically precise structure can maintain its shape for such a long period.

Rotational period

Determining Saturn’s exact rotational period has proven difficult. This is primarily because the planet is a gas giant, and different latitudes can rotate at different speeds. 

The Voyager spacecraft measurements indicated a period of about 10 hours and 39 minutes, but later measurements from the Cassini spacecraft were inconsistent with these findings.

Interior composition

Though it’s known that Saturn is primarily composed of hydrogen and helium, the exact distribution and state of these elements in its interior are not fully understood. 

The core’s composition and the transition between the core and the outer envelope are subjects of ongoing study.

Saturn’s rings

Astronomers still debate the origin and age of Saturn’s rings. Some believe the rings are as old as the Solar System, while others think they may have formed more recently. Scientists also do not fully understand the processes that govern their dynamics, stability, and longevity.

Magnetic field

The magnetic field of Saturn is unusual because it aligns almost perfectly with the planet’s rotation axis. The mechanisms that generate and maintain this magnetic field, as well as its alignment, are still unknown.

Moons’ influence

Saturn has 145 known moons, and each may have an intricate relationship with the planet and its rings. The interaction between the moons, rings, and the planet itself is complex and not yet fully explained.

Titan’s methane lakes

Titan, one of Saturn’s moons, has liquid methane lakes and rivers. The processes that cycle methane in the form of rain, rivers, and lakes – comparable to Earth’s water cycle – are intriguing and still under investigation.

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